1. Field of the Invention
The present invention relates generally to door interlock systems used in elevators. In particular, the invention concerns a door restrictor apparatus for an elevator door apparatus that prevents the elevator doors from opening when the elevator cab is between landings and not aligned with the hatchway doors of the system.
2. Description of the Related Art
In conventional elevators, an elevator car typically includes a motor to open and close the car door or doors. When the car is stopped at a landing, a clutch mechanism on the car door engages rollers on the hatchway door or doors so that the hatchway door opens and closes in unison with the car door.
One of the safety devices commonly provided on modern passenger elevators is a mechanism to prevent the car doors from opening when the car is not within a certain distance of the landing. This feature is desirable in the case of a car that has become stuck between floors, because it prevents passengers from prying open the doors in an attempt to exit the car, which could result in injury. Such devices also prevent the door(s) from opening in the event that the door motor, due to a malfunction, were to attempt to open the doors when the car is not at a landing.
U.S. Pat. No. 4,313,525, to McDonald, discloses a car door safety interlock system. In that system, a power operated sliding door of an elevator car is provided with a mechanical safety interlock which permits the car door to be moved more than a critical distance from its closed position only when the car is in a landing zone. A pivoted interlock hook on the car door has a normal position in which it engages an interlock lug on the car frame when the door moves the critical distance from closed position. A movable element on the car door is driven to move the hook to a clearance position relative to the interlock lug. Drive of the movable element occurs when it contacts an inter-engaging member on the hatch door as the car door first starts to move from closed position in a landing zone.
It is an object of the present invention to provide an improved apparatus for preventing an elevator car door from opening when the car is not within a predetermined distance of a landing.